This discovery relates to the treating of wood in order to prevent stain and decay during storage and to preserve the asethetic value and strength of wood.
Woods are known to have great variations in their decay resistance. Certain species such as western red cedar (Thuja plicata), yellow cedar (Chamaecyparis nootkatensis D. Don), yew (taxus spp.), redwood (Sequoia spp.P and teak (Tectona grandis L) are highly decay resistant. However, a large majority of the species which constitute the main volume of commercial lumber are less resistant to decay. These species, especially the sapwood, if exposed to air without kiln drying, will be subjected to fungal attack within a short period of time. In the warm summer months, the growth of fungus or wet lumber can be seen in 2 to 3 weeks. The first stage of a fungal attack produces black or blue stains. Although these biological stains do not reduce wood strength, they affect the aesthetic value of lumber. Futher growth of the fungi will result in decay which destroys the wood structure. Antistain treatment is therefore very important in lumber stored before drying or when lumber is shipped in the green condition. This is particularly important in international trade where green lumber is loaded into ships under warm and humid conditions and left for several months.
There are many commercial practices in the antistain and decay prevention treatment of lumber. The most effective chemicals are a family of chlorophenols such as pentachlorophenol and tetrachlorophenol in admixture with sodium hydroxide and borax in a water solution. The toxicity of the chlorophenol to humans and fish has been both a health and environmental concern for a considerable time. The discovery of a safe chemical with minimum toxicity is an urgent requirement for the wood industry.